Driving device for impulse counter



y 5, 1965 u. w. AUER 3,184,982

DRIVING DEVICE FOR IMPULSE COUNTER Filed June 11, 1965 United States Patent M 3,184,982 DRIVING DEVICE FQR IMPULSE (IOUNTER Ulrich Wolfgang Auer, Geneva, Switzerland, assignor to Sodeco, Socit des Compteurs de Geneve, Geneva, Switserland, a. firm Filed June 11, 1963, Ser. No. 287,062 Claims priority, application Switzeriand, July 14, 1962, 8505/62 4- Clairns. (Cl. 7d---143) This invention relates to a driving device for impulse counters, wherein the reciprocating motion of an actuating member actuated by the electrical impulses to be counted, preferably the oscillation of the movable armature of an electromagnet excited by the impulses, is converted into the progressive rotation of the cipher rolls of a counter through a double pawl arrangement cooperating with a ratchet wheel, in such a manner that during the movement of the actuating member in one direction, one pawl rotates the ratchet wheel through half a step and during the movement in the other direction, the other pawl continues the rotation of the ratchet wheel through a further half step in the same direction.

Such known devices operate by means of a rigid double lever pivotable about an axle, the said lever being connected to the movable armature of an electromagnet and having two lever arms with pawls arranged on opposite sides of the ratchet wheel circumference. Usually a socalled star wheel is used as the ratchet wheel in which the pawls of the said lever arms mesh. On attraction of the magnet armature, one pawl meshes in the toothed rim of the star and rotates it through a half step, the other pawl coming at the same time out of engagement with the star, whilst on de-energization of the magnet armature, the second pawl rotates the star wheel through a further half counting step in the same direction and the first pawl comes out of engagement with the star wheel.

However, these known driving devices have various disadvantages. Firstly, on engagement of the pawls, which of course are first accelerated out of their non-engagedposition and then strike the tooth flanks of the star wheel at a relatively great speed, heavy jolts occur and give rise to undesirable mechanical stressing of the parts and vibrations. Secondly, these devices require a large armature stroke, as the pawls must be moved not only through a stroke corresponding to the forward movement of the star wheel but also through a further path in order to come fully out of engagement with the star wheel. The large armature stroke necessitates a correspondingly high current consumption of the electromagnet. Finally, the manufacture of the pawl arrangement consisting of several individual parts and its mounting on a rotatable shaft re quires relatively high manufacturing costs.

There are on the other hand also known driving devices, wherein the said jolts are avoided by the pawls being mounted on the two lever ends in an articulated manner and being ermanently in engagement each with a ratchet wheel associated therewith, the two ratchet wheels in turn meshing with one another, in order to transmit both half step movements to a common shaft. The cost necessitated by this device is even higher than that of the devices described at the beginning, as in addition to the actual double pawl arrangement, the two pawls themselves must be mounted in an articulated manner and moreover two ratchet wheels are necessary.

The object of the present invention is to provide a driving device, which can be manufactured cheaply in large numbers and can be easily mounted and in which jolts due to the impact of the pawls on the tooth flanks of the ratchet wheel are avoided. Furthermore, in the device according to the invention only a small stroke of the recip- 3,134,932 Patented May 25, 1965 rocating parts is required; this stroke corresponds only to the travel required for one half counting step. As a result, on the one hand the current consumption of the electromagnet preferably used as actuating device is re duced, and on the other hand even impulse sequences with a high impulse frequency can be counted.

These technical advantages are obtained according to the invention by the feature that base member, mounting attachment and both levers (each terminating in a pawl) of the double pawl arrangement form a common structural unit manufactured from a plastic material which is elastic in the hardened state, both pawls being permanently in engagement with the ratchet wheel, whilst the base member is secured to the actuating member, preferably to the movable armature of an electromagnet, and means are provided to prevent rotation of the ratchet wheel through more than one half step on every pawl movement.

The structural part comprising both pawl levers may thus be made according to the invention in one working operation as a simple casting from a casting resin or even as a moulded part, has no rotatable shafts, and on mounting needs only to be connected to the movable armature of an electromagnet.

in a preferred embodiment of the invention, the ratchet wheel itself is also made of plastic.

The invention will be explained in more detail with reference to the drawings in which one embodiment of the subject of the invention is illustrated.

In the drawings:

FIGURES 1 and 2 show a side view of the embodiment in both end positions which can be occupied by the double pawl arrangement.

As shown in FIGURES 1 and 2, the driving device comprises the double pawl arrangement 1, the ratchet wheel 12 driving the cipher rolls of a counter not illustrated and the locking wheel 17. The double pawl arrangement consists of a base member 2, a mounting attachment 3 and the two levers 4 and 5 with their ends designed as driving pawls. The structural part 1 constitutes a single part made from plastic material, which can be manufactured cheaply and in large numbers as a casting, for example. The plastic used must have a certain elasticity in the hardened state, in order that on the one hand the base member 2 with the levers 4 and 5 can bear in a resilient manner against the mounting attachment 3, and on the other hand the levers themselves can be in elastic relation to the base member. For this purpose these parts are joined by webs 8 and 9, 1t), respectively. In order to give the base member 2 itself sufficient rigidity without making it too thick, its edges and central part are provided with ribs 2.

Two holes I]. serve for securing the double pawl arrangement l by means of screws to the casing of a counter, not shown. The hole diameter is preferably kept somewhat larger than the screw diameter, so that the position of the pawls relatively to the ratchet wheel. 12 as well as the necessary spring force required by the elasticity of the double pawl arrangement can be easily adjusted.

The two pawls d and 7 engage the circumference of the ratchet wheel 12, which has a toothed rim in saw tooth form, in which the larger flanks 13 extending substantially tangentially to the ratchet wheel are suitably curved. The purpose of these curved tooth flanks will be discussed later. On the shaft 14 of the ratchet Wheel 12 and rigidly connected therewith is arranged a larger ratchet wheel 15, which is in engagement with a locking wheel 17 rotatable about the shaft 16. In the embodimerit shown in FIGURES 1 and 2 the toothed rim of the locking wheel 11.7 meshing with the ratchet wheel 15 has eight teeth, only four of which can be seen in the drawing, whilst the other four are located exactly behind the four projections 12% which are arranged on the face of the locking wheel 17 nearest the observer and project partly into a recess 19 in the base member 2 of the double pawl arrangement.

The shafts l4 and 16 of ratchet wheel 12 and 15 and locking wheel 17, respectively, are mounted in the casing, not shown, of a counter. On the shaft 14 are located, for example, behind the ratchet wheel 15 the cipher rolls arranged in a known manner of a decimal counter, the cipher roll of which indicating the units may be rigidly connected to the ratchet wheel 15.

Advantageously, in addition to the actual double pawl arrangement, the ratchet wheel 12, the ratchet wheel 15 and the locking wheel 17 are also made of plastic.

The structural part 1 is connected to the driving actuating member, which is usually the movable armature of an electromagnet. in the embodiment in question an appendage 22 of this armature of the electromagnet indicated by a coil 32 in FIGURE 1 is secured in a recess on the base member of the structural part l. The double pawl arrangement and the movable armature part of the electromagnet are in their rest position in FlGURE l, whilst in FIGURE 2 the pos, -on of the movable armature and hence of the double pawl arrangement is shown in the attracted state of the armature.

In the rest position shown in FEGURE l the lever is pressed in the region of its bent portion, owing to the elasticity of the double pawl arrangement, against a stop Ztl rigidly connected to the casing, not shown, of the counter. The pawls 6 and 7 of the two lovers are, likewise owing to the elasticity of the material, pressed against the toothed rim of the ratchet wheel 12. When the movable armaturc of the magnet is attracted, the armature bends the entire double pawl arrangement as shown in FIGURE 2 to the right until the lever 5 bears against the other stop 21 likewise connected to the casing of tie counter.

The bending point about which the base mem -er 2 and the levers tand 5 rotate relatively to the mounting attachment 3, is located in the web 8, the cross section of which is made to this end substantially smaller than the cross sections of the base member and the mounting attachment. During this movement the pawl 6 of the lever 4 rotates the ratchet Wheel 12 through a half counting step of the counter, whilst the pawl 7 of the lever 5 comes into abutment with the radially directed flank of the next tooth of the ratchet wheel 12. On de-energization of the movable armature the pawl arrangement, owing to its elasticity, eturns again to the rest position shown in PEG- URE l, the ratchet wheel this time being rotated by the pawl 7 of the lever 5 through a half tooth graduation, that is to say again through a half counting step.

In order to prevent the ratchet wheel 12 during the attraction movement of the armature being rotated through more than one half tooth graduation owing to the momentum, the four projections 18 of the locking wheel project into the recess 1? of the pawl arrangement, so that the projection indicated in FIGURE 2 at 155 abuts against the edge 34 or" the recess 19 on continuation of the rotation in anti-clockwise direction and locking wheel and ratchet wheel 12 are thus locked.

In the same way, on de-energization of the armature, the edge of the recess 19 indicated in FIGURE 1 at 33 prevents further rotation of the locking wheel 1?, as its projection 18 shown in FTGURE 1 would abut against this edge 33. As shown in FEGURES l and 2, the levers dand 5 are angled oil at the bending points 9 and it) by an angle differing through ninety degrees relatively to the longitudinal axis of the double pawl arrangement. As a result of this the bending point of the levers situated at the places of maximum curvature at 9 and it? has in each case a distance from the straight line passing through the horizontal diameter of the locking wheel which is greater than the radius of the ratchet wheel 12. The force exerted on the pawl end during the driving of the ratchet wheel 12 acts in a direction tangential to the ratchet wheel and produces owing to the described position of the bending points of the lovers a torque which tends to rotate the pawl 6 or 7 which is driving at the time in a direction towards the centre of the ratchet wheel 12 and in this way ensures a secure engagement of the pawl in the toothed rim. At the same time the non-driving pawl undergoes, owing to the torque exerted by the friction force on the pawl lever a force component reducing the contact pressure on the ratchet wheel 12.

In order to keep the internal stresses at the bending points of the lever during bending by the external forces as small as possible, the tooth flanks 13 of the ratchet wheel 12 extending approximately radially are not flat but are curved. In this way the height of the radial flanks and hence the deflection of the levers directed radially to the ratchet wheel 12 during rotation of the ratchet wheel through one tooth graduation are also kept small. At the same time through the curved surface of the tangential tooth flanks the result is obtained that the radial deflection and hence the increasing of the internal stress of the levers is an at least substantially linear function of the angle of rotation of the ratchet wheel. Through the small height of the radial tooth flanks, the impact of the pawls when sliding from the end of one tangential tooth flank to the next is moreover kept small.

The driving device described is characterized by simple manufacture and assembly, as the one-part double pawl arrangement requires neither a rotatable shaft nor a combination of parts. Further, the torque necessary for actuatin' the device is very small, as only slight friction resistances have to be overcome between the pawls and the ratchet Wheel flanks as Well as the small deformation resistance of the pawl arrangement. This small torque in conjunction with the small working stroke permits the use of weak electromagnets.

What is claimed is:

l. A driving device for electric impulse counters of the type comprising a base member, an actuating member to which the electric impulses to be counted impart a to-andfro movement, a ratchet wheel for operating the counter, a plastic member mounted on said base for flexible deformation by said actuating member and having two pawls in engagement with said ratchet wheel for rotatively driving same, said driving device being characterized by the fact that each of said two pawls is mounted at the extremity of a lever, said two levers which are integral with, and protrude from, said actuating member, being oppositely turned and substantially parallel to the direction of displacement of said actuating member, said two pawls being substantially tangent to the periphery of said ratchet W1 eel and diametrally positioned with respect to said wheel, locking means being provided to limit the amount of rotation of said ratchet wheel by the respective pawls as said plastic member is flexed and restored.

2. A driving device for electric impulse counters as claimed in claim 1, comprising a gear wheel mounted to rotate with said ratchet wheel and a locking wheel meshing therewith and mounted on said base member, the movement of said locking wheel checked by said plastic member when the required amount of rotation has been effected.

3. A driving device for electric impulse counters of the type comprising a base member, an actuating member to which the electric impulses to be counted impart a to-andfro movement, a ratchet wheel for operating the counter, a plastic member mounted on said base for flexible de formation by said actuating member and having two pawls in engagement with said ratchet wheel for rotatively driving same, said driving device being characterized by the fact that the said actuating member is the movable armature of an electro-rnagnet and that each of said two pawls is mounted at the extremity of a lever, said two levers which are integral with, and protrude from, said movable armature, being oppositely turned and substantially parallel to the direction of displacement of said movable armature, said two pawls being substantially tangent to the periphery of said ratchet wheel and diametrally positioned with respect to said wheel, locking means being provided to limit the amount of rotation of said ratchet wheel by the respective pawls as said plastic member is flexed and restored.

4. A driving device for electric impulse counters of the type comprising a base member, an actuating member to which the electric impulses to be counted impart a to-andfro movement, a ratchet wheel for operating the counter, a plastic member mounted on said base for flexible deformation by said actuating member and having two pawls in engagement with said ratchet wheel for rotatively driving same, said driving device being characterized by the fact that the said actuating member is the movable armature of an electric magnet and that each of said two pawls is mounted at the extremity of a lever, said two levers which are integral with, and protrude from, said movable armature, being oppositely turned and substantially parallel to the direction of displacement of said 20 movable armature, said two pawls being substantially tangent to the periphery of said ratchet wheel and diametrally positioned with respect to said wheel, locking means being provided to limit the amount of rotation of said ratchet wheel by the respective pawls as said plastic member is flexed and restored, a gear wheel being mounted to rotate with said ratchet wheel and a locking wheel meshing with said gear wheel and being mounted on said base member, the movement of said locking Wheel being checked by said plastic member when the required amount of rotation has been effected.

References Cited by the Examiner UNITED STATES PATENTS 1,979,028 10/ 34 Ewart 74-143 2,943,512 7/ 6O Nicolaus 74-575 3,142,149 7/64 Hays 74-159 FOREIGN PATENTS 624,331 6/49 Great Britain. BROUGHTON G. DURHAM, Primary Examiner. 

1. A DRIVING DEVICE FOR ELECTRIC IMPULSE COUNTERS OF THE TYPE COMPRISING A BASE MEMBER, AN ACTUATING MEMBER TO WHICH THE ELECTRIC IMPULSES TO BE COUNTED IMPART A TO-ANDFRO MOVEMENT, A RATCHET WHEEL FOR OPERATING THE COUNTER, A PLASIC MEMBER MOUNTED ON SAID BASE FOR FLEXIBLE DEFORMATION BY SAID ACTUATING MEMBER AND HAVING TWO PAWLS IN ENGAGEMENT WITH SAID RATCHET WHEEL FOR ROTATIVELY DRIVING SAME, SAID DRIVING DEVICE BEING CHARACTERIZED BY THE FACT THAT EACH OF SAID TWO PAWLS IS MOUNTED AT THE EXTREMITY OF A LEVER, SAID TWO LEVERS WHICH ARE INTEGRAL WITH, AND PROTRUDE FROM, SAID ACTUATING MEMBER, BEING OPPOSITELY TURNED AND SUBSTANTIALLY PARALLEL TO THE DIRECTION OF DISPLACEMENT OF SAID ACTUTING MEMBER, SAID TWO PAWLS BEING SUBSTANTIALLY TANGENT TO THE PERIPHERY OF SAID RATCHET WHEEL AND DIAMETRIALLY POSITIONED WITH RESPECT TO SAID WHEEL, LOCKING MEANS BEING PROVIDED TO LIMIT THE AMOUNT 